NDLI: Study of $Fe^{3+}-sapphire$ maser above 4K

Content Provider	IEEE Xplore Digital Library
Author	Benmessai, K. Mrad, M. Creedon, D.L. Le Floch, J. Tobar, M.E. Bourgeois, P. Kersale, Y. Giordano, V.
Copyright Year	2011
Description	Author affiliation: Frequency Standards and Metrology, School of Physics, The University of Western Australia, Perth, WA, Australia (Benmessai, K.; Creedon, D.L.; Le Floch, J.; Tobar, M.E.) \|\| Departement Temps Fréquence, Femto-st Institut, University of Franche Comté, BESANCON, France (Mrad, M.; Bourgeois, P.; Kersale, Y.; Giordano, V.)
Abstract	The Whispering Gallery Mode Maser Oscillator (WHIGMO) uses paramagnetic $Fe^{3+}$ ions in HEMEX sapphire at low temperature, and has been described in many previous publications [1–7]. The fractional frequency instability has been demonstrated to be as low as σy(1s<τ<100s) = $10^{−14}.$ This instability is normally measured at the frequency-temperature turnover point of the sapphire where the effects of temperature fluctuations on frequency are nullified to first order [8–9]. Usually the temperature is determined by the relative concentrations of several paramagnetic ions such as Cr3+, Mo3+, and Ti3+. In this paper, we show that Fe3+ ions have a strong effect on the turnover point. We compare the behavior of two crystals — “Pinocchio” (concentration of active Fe3+ ions = 10ppb) and “Geppetto” (100ppb). We also report the observation of an upper limit for maser operation above 30K. This limit is explained using a Boltzmann distribution for the active ion, and we show that the populations of the energy levels are so close at this temperature that the effect of the pump at 31 GHz used to create the maser at 12 GHz is ineffective.
Starting Page	1
Ending Page	5
File Size	1125558
Page Count	5
File Format	PDF
ISBN	9781612841113
ISSN	10756787
e-ISBN	9781612841120
DOI	10.1109/FCS.2011.5977798
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2011-05-02
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Masers Temperature measurement Ions Frequency measurement Resonant frequency Crystals Oscillators
Content Type	Text
Resource Type	Article

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